The present invention relates to dispensers for dispensing lengths of a sheet material, which dispensers include a hub rotatably mounted on the frame from only one end, on which hub a roll of sheet material is supported; and which dispensers also include an elongate cut-off blade also attached to the frame from only one end that has a cutting edge spaced from and extending generally parallel to the axis of the hub so that a user of the dispenser can manually tension sheet material being pulled from the roll around the cutting edge to sequentially transversely sever the sheet material.
U.S. Pat. No. 4,990,214 describes a portable dispenser called a masking machine or device for dispensing lengths of a sheet material, one embodiment of which is sold by Minnesota Mining and Manufacturing Company, St., Paul, Minn. under the trade designation xe2x80x9cHandMaskerxe2x80x9d (t.m.) M3000 Dispenser. Generally, that dispenser includes a polymeric frame on which are rotatably mounted two hubs, one adapted to receive a roll of masking sheet material, and the other adapted to receive a roll of tape. Tape from that roll is guided to the periphery of the roll of masking sheet material where a side portion of the tape is adhered to a portion of the masking sheet material to form a composite masking sheet material having an exposed portion of the coating of pressure sensitive adhesive on the length of tape so that the exposed portion of the coating of adhesive can be adhered along a surface to be masked to hold the composite masking sheet material in a desired position.
A person may pull the composite masking sheet material formed at the periphery of the roll of masking sheet material from the dispenser by either holding the dispenser while pulling on the composite masking sheet material or by moving the dispenser away from the composite sheet material as it is adhered along a surface. A cut-off blade is attached at one end on the frame and extends generally parallel to the axes of the hubs to define a first side of a passageway through which the composite masking sheet material is pulled from the dispenser. A user of the dispenser can manually tension composite masking sheet material being pulled from the dispenser around a row of projecting teeth included in the cut-off blade that will pierce and then transversely sever the tensioned composite masking sheet material starting from the edge of the composite masking sheet adjacent the frame and progressing toward the distal end of the cut-off blade. The cut-off blade is particularly useful for severing composite masking sheet material when the masking sheet material is folded polymeric sheet material of the type described in U.S. Pat. No. 5,113,921. Such piercing by the teeth will advantageously help to maintain the relative positions of the layers of folded polymeric masking sheet material while it is being cut, however, the resultant cut edge on the composite masking sheet material is often not as straight and as close to a right angle to the longitudinal edges of the tape and masking sheet material as may be desired for certain applications of the composite masking sheet material. Applicant has determined that this problem with the resultant cut edge is due to two problems: (1) flexing of the cut-off blade toward the roll as the composite masking sheet material is progressively cut along the cutting edge toward the distal end of the blade; and (2) a slight progressive unwinding of the roll of masking sheet material as the composite masking sheet material is progressively transversely cut on the cut-off blade.
The present invention provides a modification for a masking machine or device for dispensing lengths of sheet material generally of the type described above that will help the masking machine produce a cut edge on the sheet material that is significantly straighter and closer to a right angle to the longitudinal edges of the sheet material than the cut that is produced by the masking machine or device without the modification, especially when the sheet material dispensed from the device is folded polymeric sheet material.
Generally, the dispenser according to the present invention is for dispensing a length of sheet material from a roll of that sheet material. The dispenser comprises a first hub rotatably mounted on the frame at a first end of the hub that supports the roll of sheet material around its periphery. An elongate cut-off blade has a proximal end attached to the frame and a cutting edge spaced from and extending generally parallel to the axis of the first hub to a distal end of the cut-off blade so that a user of the dispenser can manually tension sheet material being pulled from the dispenser around the cutting edge to sequentially transversely sever the sheet material. The dispenser according to the present invention includes the improvement of a cut-off blade/supply roll spacing assembly that includes (1) a spacing arm, and (2) a locating hub mounted on a second end of the spacing arm. The locating hub is adapted to be received in an opening in the roll of sheet material from a second end of the roll opposite its first end that is adjacent the frame of the dispenser. An opposite first end of the spacing arm is mounted on the cut-off blade adjacent its distal end so that the spacing arm and locating hub space the cutting edge a predetermined distance from the axis of the roll of sheet material at the second end of the roll of sheet material that is a slightly greater distance (e.g., about 0.31 inch or 0.79 cm greater) than the distance between the cutting edge and the axis of the roll of sheet material at the first end of the roll of sheet material as the sheet material is sequentially transversely cut along the cutting edge on the blade. This both (1) restricts the cut-off blade from flexing toward the roll as the sheet material is progressively cut along the cutting edge from the proximal end toward the distal end of the cut-off blade; and (2) accommodates the slight progressive unwinding of the roll of sheet material as the sheet material is progressively transversely cut on the cut-off blade to produce a cut edge on the sheet material that, while not precisely a right angle, is closer to a right angle with respect to the longitudinal edges on the sheet material than is typically produced on the same dispenser without the cut-off blade/supply roll spacing assembly.